có 2 hộp bút. mỗi hộp 10 cái, hộp 1 có 3 bút trắng và 7 bút nâu, hộp 2 có 4 bút trắng và 6 bút nâu. từ hộp 3 lấy ra 1 chiếc bút. tính xác suất bút nâu?

The number of hours per week that the television is turned on is determined for each family in a sample. the mean of the data is 37 hours and the median is 33.2 hours. twenty-four of the families in the sample turned on the television for 22 hours or less for the week. the 13th percentile of the data is 22 hours. approximately how many families are in the sample? round your answer to the nearest integer.

Aquadratic equation in standard from is written ax^2= bx+c, where a,b and c are real numbers and a is not zero?

Use the method of cylindrical shells to find the volume v generated by rotating the region bounded by the curves about the given axis.y = 7ex, y = 7e^-x, x = 1; about the y-axis